1. Field of the Invention
The present invention relates to an air filtering apparatus that can remove microorganisms floating in the air such as bacteria, virus, fungus, etc. (hereinafter merely referred to as “virus, etc.”), and more particularly to an air filtering apparatus having a mechanism for detecting water exchange timing.
2. Description of the Related Art
There has been proposed a filtering apparatus in which tap water is electrolyzed to generate electrolytic water containing active oxygen species such as hypochlorous acid or the like, and virus, etc. floating in the air are removed by using this electrolytic water (for example, see JP-A-2002-181358). According to this filtering apparatus, electrolytic water is supplied to a humidifying element formed of non-woven cloth or the like, and virus, etc. in the air are brought into contact with the electrolytic water in the humidifying element to inactivate the virus, etc., thereby filtering the air.
In the filtering apparatus described above, a part of the electrolytic water supplied to the humidifying element is vaporized and the remaining electrolytic water is drained. Therefore, in order to effectively use electrolytic water, the applicant of this application has proposed an air filtering apparatus utilizing circulation of electrolytic water. According to this air filtering apparatus, it is possible not only to effectively use electrolytic water, but also to reduce the running cost by suppressing water consumption.
When electrolytic water is circulatively used for a long term, the electrolytic water is polluted and this pollution causes reduction in electrolysis performance, so that the air filtering performance itself is reduced. In order to solve this problem, it may be considered that water exchange is periodically carried out every time a predetermined time elapses. However, the pollution degree of electrolytic water is varied in accordance with not only the circulation time of the electrolytic water, but also the environment under which the air filtering apparatus is set. Accordingly, it is difficult to accurately control the timing of water exchange on the basis of the circulation time.